Centrifugal well pumps are commonly used for pumping oil and water from oil wells. The pumps have a large number of stages, each stage having a stationary diffuser and a rotating impeller. The rotating impellers exert a downward thrust as the fluid moves upward. Also, particularly at startup and when the fluid flow is nonuniform, the impellers may exert upward thrust. In the most common pump design, the impellers float freely on the shaft so that each impeller transfers downward thrust to one of the diffusers. A thrust washer or bearing is located between a portion of each impeller and the upstream diffuser to accommodate the downward thrust. Another thrust washer transfers downward thrust.
Some wells produce abrasive materials, such as sand, along with the oil. The abrasive material causes wear of the pump components, particularly in the areas where downward thrust and upward thrust are transferred. Tungsten carbide thrust bearings and bearing sleeves may be employed in these pumps to reduce wear. A number of designs for these components exist, but improvements are desirable.